So say I have a world miles ahead of what we have in technological terms today, which, without getting into too much detail, has a power system that is universally used across the globe. (Save for parts of the middle east and Africa.) It uses large substations for entire regions. It is an interconnected system, but not necessarily connected to the internet. What would be the most surefire way to completely knock out the power, sending a world so reliant on tech into a anarchy? Either a natural disaster or some sort of targeted attack seems like it would work but I'm not exactly sure how.
Furthermore, what would happen to society? How would people in such an advanced world react? How would governments even cope about something like this?